Sex significantly influences transduction of murine liver by recombinant adeno-associated viral vectors through an androgen-dependent pathway

Abstract

A systematic evaluation of the influence of sex on transduction by recombinant adeno-associated viral vector (rAAV) indicated that transgene expression after liver-targeted delivery of vector particles was between 5-to 13-fold higher in male mice compared with female mice, irrespective of the proviral promoter or cDNA and mouse strain. Molecular analysis revealed that the rAAV genome was stably retained in male liver at levels that were 7-fold higher than those observed in females. Further, the sex difference in transduction was observed with AAV-2-and AAV-5-based vectors, which use distinct receptor complexes for infection. In concordance with the differences in AAV transduction, gel shift analysis with nuclear extracts derived from the liver of mice and humans revealed substantially higher binding of host nuclear protein to the rep-binding site (RBS) of AAV inverted terminal repeat (ITR) in males compared with females. Transduction efficiency and binding of nuclear protein to RBS was dramatically reduced in male mice by castration. In contrast, although oophorectomy did not significantly influence rAAV transduction, administration of 5␣ dihydrotestosterone, prior to gene transfer, increased stable hepatocyte gene transfer in females to levels observed in male mice, implying that androgens significantly influence hepatocyte gene transfer. Interestingly, sex did not have a significant effect on AAV gene transfer into nonhepatic tissue, indicating that there are distinct tissue-and sex-specific differences in the mechanisms responsible for efficient transduction with this vector. These results have significant implications for gene therapy of autosomal and acquired disorders affecting the liver. IntroductionRecombinant adeno-associated viral (rAAV) vectors are proving to be highly effective vehicles for the gene therapy of disorders that affect the liver such as hemophilia, ␣1 antitrypsin deficiency, and mucopolysaccharidosis. [1][2][3] The success of these vectors can be ascribed to the fact that they are able to mediate persistent therapeutic expression of transgene such as coagulation factor IX (FIX) in murine and canine models of hemophilia B after portal vein administration of vector particles. [4][5][6][7][8][9][10][11][12] Recently, we have demonstrated sustained expression (Ͼ 18 months) of human FIX (hFIX) at 4% to 10% of physiologic levels in a nonhuman primate model following liver-targeted delivery of AAV vector genomes. 1 Other advantages afforded by AAV vectors include the best safety profile among gene transfer vectors of viral origin as wild-type AAV has never been associated with any human disease. Safety is further enhanced by the dependence of AAV on coinfection with helper virus (usually adeno or herpes virus) for productive infection. Additionally, recombinant vectors are entirely devoid of wild-type viral genes, thus reducing the potential for invoking cell-mediated immune response to foreign viral proteins. 13 These attributes have led to a phase 1 to 2 study to evaluate the safety of rAAV ...

Long-term correction of hyperphenylalaninemia by AAV-mediated gene transfer leads to behavioral recovery in phenylketonuria mice

“…The underlying mechanisms for these female-specific phenomena are currently unknown. Davidoff et al 22 recently reported similar observations that AAV2-and AAV5-derived vectors less efficiently transduced livers of female mice than males. They suggested that the difference was due to an androgen-dependent pathway for augmenting hepatocyte transduction, but its mode of action is undetermined.…”

Induction of hepatocellular carcinoma by in vivo gene targeting

“…All of the vector-injected male mice from each cohort had liver tumors, but there was a relative delay in tumor formation in female mice, with 50%, 75%, and 100% of females developing tumors at 6 mo, 10 mo, and the time of being killed, respectively. The delay in females may have been due to decreased transduction (22) or hormonal effects on HCC development (23). The number of tumors increased with time, as did liver weight, also with a delay in females ( Fig.…”

Administration-route and gender-independent long-term therapeutic correction of phenylketonuria (PKU) in a mouse model by recombinant adeno-associated virus 8 pseudotyped vector-mediated gene transfer

“…Indeed, liver transgene expression of rAAV vectors in males is five to 13-fold higher than in females, and this difference is mainly caused by androgens. 40 However, the detailed mechanism is unclear and other hepatic factors might also be involved since the difference occurred specifically in liver.…”